1. Field
Embodiments described herein generally relate to systems and methods for testing electrical devices.
2. Background
Package-on-package (POP) devices include two or more packaged devices (e.g., integrated circuit (IC) devices) stacked on top of one another. In one example, a POP device can include a memory stacked on top of a memory controller. In such an example, the memory controller controls access to the memory device stacked on top of it. For example, the POP device including the memory and memory controller can be mounted on to a printed circuit board (PCB), which can electrically couple the POP device to other devices mounted on it. In such an example, the memory controller can regulate how other components store and retrieve information from the memory.
In a POP device, at least one of the stacked devices typically includes connection elements on at least two surfaces. For example, for a memory stacked on a memory controller, the memory controller can include connection elements on its top surface (to communicate with the memory) and on its bottom surface (to communication with a PCB). Thus, when the memory controller is tested, communications with both the top and bottom sets of connections elements must be tested.
One approach for testing a memory controller having connection elements on both its top and bottom surfaces is to use an actuator to physically acquire the memory controller. The actuator physically places the memory controller into a socket of a device interface board (DIB). The socket establishes electrical connections with the memory controller's bottom surface connection elements. The top surface connection elements can be routed to the DIB through the actuator. To test the interaction of the memory controller with a memory, the DIB can emulate the operation of a memory.
The emulation approach to testing the memory controller suffers from a number of drawbacks. First, the emulation provided by the DIB is relatively slow compared to memories with which the memory controller will be used. Thus, emulation often does not accurately mimic real world operation and it requires more testing time than if testing was conducted using an actual memory. Also, the emulation approach requires relative long signal paths from the top surface connection elements to the DIB, Because of signal integrity issues associated with those long paths, the emulation approach often only uses DC testing schemes.
The disclosed subject matter will now be described with reference to the accompanying drawings. In the drawings, like reference numbers indicate identical or functionally similar elements. Additionally, the left-most digit(s) of a reference number identifies the drawing in which the reference number first appears.